Should I Avoid GMO’s?

For my very first review, let’s start with a controversy everyone is familiar with: Genetically Modified Organisms (GMOs/GM foods) also referred to as genetically engineered (GE foods). Full disclosure, I bit off way more than I could chew for this one. If anyone is interested in investigating a more narrow subcomponent of GMO safety, let me know and I’ll revisit the topic. There was just no way to thoroughly evaluate all the literature here without spending another 2 years in grad school.

So, what exactly are genetically modified foods?

These are seeds or even animals in which scientists physically change the DNA on purpose. For example, they might put genes from bacteria into corn DNA. This does not happen in nature. Why would they want to do this? Usually it’s so they can spray herbicides (Roundup) and pesticides without harming the crops. Sometimes it’s to make the food taste better or become easier to eat. Sometimes, it’s to add nutrients, like beta-carotene, to less nutrient dense foods, such as rice.

One of this biggest fears people originally had when scientists started making genetic modifications was that they could be putting allergenic proteins into otherwise harmless foods. There was a specific kind of genetically modified corn (StarLink), that caused anaphylactic reactions in a few people who ate taco shells made from that corn. This corn had not been tested or approved for human consumption and accidentally wound up in some crops. Since then, safety standards have increased.

Scientists must compare the new proteins they add to a food to a list of proteins that tend to cause allergic reactions in people. This list includes the proteins from foods which cause 90% of allergic reactions: milk, eggs, fish, shellfish, tree nuts, peanuts, wheat, and soy. If there is any way the body could mistake the new protein for an allergen, it can’t be approved. For example, one team wanted to increase the nutritional content of soybeans by adding a protein from a Brazil nut. Their research showed that people who were allergic to Brazil nuts might have a reaction if they ate products made from these soybeans. So they discarded the idea.

It’s important to remember that if a person was allergic to conventional soybeans, they’ll probably be allergic to GM soybeans too. However, there are some experiments underway that use GM to REMOVE allergens. Although it is not available yet, scientists are trying to genetically modify wheat so that it won’t harm people with celiac disease (please don’t start thinking about gluten just yet…I’m saving that for another review).

Other concerns that have come up include a wide range of illnesses from cancer and infertility to autism and Alzheimer’s. You name it and GM foods have been blamed! A huge portion of the debate is actually more about Roundup (glyphosate) than the actual GM foods. Glyphosate works by stopping an enzyme pathway necessary for plant growth. This pathway is only in plants and some microorganisms, but not in animals or people. This means glyphosate kills all plants except plants that have been genetically modified to withstand it.

Here is my somewhat preliminary review of GM food safety. Like I said above, let me know if there is interest in digging deeper into a more specific area.

  1. The claim/question: Are there any health risks associated with eating genetically modified foods?
  • 2. Results from a quick initial search
    • Here are some of the most popular sources I found for anti-GMO claims:
      • European Network of Scientists for Social and Environmental Responsibility
      • Institute for Responsible Technology
      • Care2Healthy Living
      • Food and Water Watch
      • Mother Jones
      • Center for Food Safety
      • Collective Evolution
    • They claim GMOs can cause some pretty big problems:
      • Health Issues: animal studies associate GM foods with infertility, immune problems (allergies), accelerated aging, cancer, antibiotic resistance, pesticide exposure, faulty insulin regulation, damage to the liver and pancreas, changes to the microbiome of the gastrointestinal system and several other health problems.
      • Environmental risks: chemical pollution, super-weeds and cross-contamination
      • Lack of study: GMOs have not been studied for their safety. The biotech industry has been allowed to use the people as guinea pigs. After all, they’ve only been around for about 20 years.
    • And some of the most popular sources refuting the anti-GMO claims:
      • World Health Organization
      • American Medical Association
      • US National Academy of Sciences
      • Health Canada
      • Food Standards Australia
      • British Medical Association
      • French Academy of Sciences
      • Many major new sources
    • They claim GMOs are just as safe as conventionally grown foods, if not safer. They say:
      • GM foods are among the most well studied subjects in science with thousands of studies showing they are safe.
      • There is a world-wide scientific consensus on GM safety
      • There is a scientific consensus that GM farming does not harm the environment or negatively impact farmers
      • They describe benefits of GM foods such as “golden rice” which provides necessary nutrients to people in the developing world
  • 3. Follow-up Questions: The preliminary search has made me want to ask so many follow-up questions on this topic! What a can of worms!
    • How do you figure out which sources are credible when you find peer reviewed articles on both sides of the debate?
      • Are the studies or websites funded by the company selling the product or by independent scientists? If someone is making a profit, beware of the research findings.
      • Number and quality of studies on each side: no one study can prove anything, so what does the majority say? Are there critical flaws in the research designs?
      • Who did the research and what are their credentials?
      • Have scientists responded to the more alarming studies?
  • 4. Links and comments from readers…none yet! But I’d love to know what you think!
  • 5. Peer-reviewed sources

 

    • Due to the amount of research available on this topic, I have relied heavily on meta-analyses. These are peer reviewed articles that review many other articles to draw broad conclusions. I read abstracts and conclusions available on PubMed for more than 100 articles relevant to health. Here are some that I found. I will need to limit my search to more narrow topics to find more good meta studies. Many found small statistically significant differences in various measurements between the test groups and control groups.
    • Meta-analysis: 1783 studies reviewed by a team of Italian scientists. Studies were chosen based on date (2003-2013) and quality of study. 312 of the studies looked at effects on “consumption” while the remainder reviewed environmental effects, public perception, gene flow and other factors. Most of these 312 studies were done on animals due to ethics and confounding variables associated with human trials. No adverse health effects were found in animals who ate GM crops versus control groups who ate conventional crops.
      • And here’s a link to how each one was refuted: https://www.geneticliteracyproject.org/2015/11/13/10-studies-proving-gmos-are-harmful-not-if-science-matters/
      • Below, I have outlined the claims made by each of these studies or by people who interpreted the studies, followed by responses from GMO supporters.
        • Claim: Pesticides associated with GM foods were found in fetal and maternal blood.
          • Refutation: The system used to detect the toxins was for plants, not animals. The people in the study would have had to eat several kilograms of corn in order for the amounts reported to have been accurate. Also, humans don’t have the receptors to absorb the specific pesticide toxins. No harm could have been caused by tiny amounts of pesticide proteins that humans can’t even absorb.
        • Claim: GM wheat associated with celiac disease, intestinal permeability, and digestion problems.
          • Refutation: GMO wheat is not available for purchase. The Celiac Disease Foundation has spoken out against this claim. There is actually no article anywhere that even studied this hypothesis.
        • Claim: DNA from genetically modified crops can be transferred to humans
          • Refutation: The article actually concluded that they found whole genes from plants in human blood. This occurs when you eat any type of plant, GM or conventional
        • Claim: Genetically modified corn caused tumors in rats
          • Refutation: These rats were genetically predisposed to tumors. The paper was retracted due to many flaws.
        • Claim: Glyphosate (herbicides) used on GM crops may cause breast cancer
          • Refutation: This was tested on in-vitro cells which often do not transfer to real life organs. The researchers did not suggest that the herbicides caused cancer, but that it may proliferate the cancer. The study has not been repeated, but similar studies did not produce the same findings. Keep in mind that the herbicide, not the GM plant is what may have caused the cancer to grow faster.
        • Claim: Glyphosate is linked to birth defects, autism, Parkinson’s and Alzheimer’s
          • Refutation: No peer reviewed studies have made this claims. They were made by anti-GMO activists without supporting evidence.
        • Claim: Glyphosate found in urine and found in higher concentrations in chronically ill people
          • Refutation: This article appeared in a journal with a reputation for reporting overly hyped claims. The study had many flaws including: not identifying the people’s diets, health status, whether they washed their food, etc.
        • Claim: GM animal feed causes stomach inflammation in pigs
          • Refutation: This study had several important flaws including: researchers did not account for other differences in feed that have known impacts on inflammation
        • Claim: Current GMO testing mechanisms are not good enough to ensure safety
          • Refutation: The studies reviewed here are not scientific or peer reviewed.
  • 6. What we know and don’t know

 

    • After reviewing, I learned that there is a lot more to learn on this topic that I could have ever imagined! Every study has a counter-study. Both sides are all in when it comes to the safety (or lack thereof) of GM foods. We know that both scientists and laypeople have raised concerns about the possible health threats of GMOs. These concerns range from allergies to cancer. At least a few scientific, peer-reviewed articles have been published that seem to suggest the health concerns are legitimate. But, we also know that the majority (about 90% of scientists) believe GM foods are as safe as or safer than conventional foods. They have refuted the articles reporting adverse health effects by showing important flaws in the designs of the studies. They have reviewed at least 1700 published peer-reviewed studies which suggest (but cannot prove) safety.  These scientists come from many different countries and universities which increases their credibility.
    • Much of the research demonstrating GMO safety was done by companies, like Monsanto, who sell GM plants. This causes bias. However, these companies are legally required to test their products so it should come as no surprise that they…tested their products.
    • Most of the health concerns raised are actually related to the pesticides used, not the GM crop itself.
  • 7. My conclusions

 

    • So, what have I decided to do with this information? I will buy, and eat genetically modified foods. I hope more opportunities arise for GM foods that can help poor people who can’t get adequate nutrition.
    • However, I don’t know how strong the scientific consensus is when it comes to health risks. It seems like the best articles are all about the environmental impact, pesticide use, farmer profits, and feed-animal health. There really aren’t great studies addressing human health concerns.  I’ll still pay attention when health concerns are raised, but I’ll always check to see how scientists respond to new claims.
    • I WILL WASH MY FOOD! Getting rid of the pesticide residue is a no-brainer. If any of the health concerns are truly legitimate, they are likely related to pesticides/herbicides rather than genetic modification. Nearly all produce is treated with pesticides and/or herbicides regardless of whether or not they are GM. Unfortunately, packaged foods and meat will probably have some herbicide residue that I won’t be able to wash off.
    • Additionally, I like to shop locally when I can and I’m still a bit wary of big agri-business. I like the idea of family owned, locally grown farms that don’t waste tons of energy transporting their products around the world. Maybe I’ll look into re-activating that CSA subscription.
  • If you have a peer reviewed study that makes a claim I didn’t cover or seems to suggest conclusions different from what I’ve found, I’d love to read it!

Author: Tara

Skeptical health and fitness enthusiast (and also speech-language pathologist)

2 thoughts on “Should I Avoid GMO’s?”

  1. Reading this in between clients at work! Truly fascinating study, thank you so much for pin-pointing my main questions/concerns on this topic as I raise two young, picky eaters!

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